prints go bad after a cm high or so?

Does anyone have any suggestions for these prints? After calibrating like Dave Durant suggests and getting the 20mm X 10mm calibration block looking pretty decent at 100% infill, when I print taller objects the filament seems to start to have issues. I don't know if it is extruder temp, no fan, calibration issues or what?

Running a Mendel prusa, ramps 1.4 using, RepetierHost, modified wildseyed .041 nozzle, thermistor buried in heater block (solid steady temps), heated glass bed, 35mm/s, .25mm layers, no fan. 180C with these. I had temp higher at 194C, but more ooze at higher temp and seemed unnecessarily high because that plastic Natureworks 4043D PLA extrudes down to 160C. The spec says its melt point is 135C, so I am working my way down.

The 10% infill snowman base on the left, herringbone extruder gear on the right 100% infill. After the gear lost itself, I tried using a fan and got some amount of recovery higher as the extruder slowly decreased temp. I had no insulation on the heater block at this point temporarily after fixing an extruder jamb, so the fan caused the extruder temp to drop. As it dipped to 175-170C it seemed to recover some detail. That makes me wonder if lower extrusion temp or a fan or both could help or maybe something else?